=== modified file 'sites/all/modules/contrib/memcache/memcache.inc'
--- memcache.inc	2010-07-12 21:04:42 +0000
+++ memcache.inc	2010-08-16 23:00:49 +0000
@@ -57,6 +57,8 @@ class MemCacheDrupal implements DrupalCa
     }
     // Check if the item being fetched matches any prefixes.
     foreach ($memcached_prefixes[$this->bin] as $prefix) {
+      // The prefix will not match unless converted to a full key.
+      $prefix = dmemcache_key($prefix, $this->bin);
       if (substr($cid, 0, strlen($prefix)) == $prefix) {
         // On a match, check if we already know the current counter value.
         if (!isset($memcached_counters[$this->bin][$prefix])) {